Re: Ada 2012: In-out parameters for functions

[Niklas Holsti <niklas.holsti@tidorum.invalid>]

On 13-05-04 02:29 , Randy Brukardt wrote:

> I agree that named notation should include the direction of the parameter, 
> but again its way too late to fix. The best syntax would have been
>      Proc (In_Param => A, Out_Param <= B, In_Out_Param <=> C);
> but unfortunately "<=" is used for less-than-or-equals and trying to use it 
> in this context would be ambiguous.
> 
> So the best practical syntax would be:
>      Proc (In_Param -> A, Out_Param <- B, In_Out_Param <-> C);

How about reusing the mode keywords:

   Proc (
      In_Param  => in A,
      Out_Param => out B,
      In_Out_Param => in out C);

The mode keywords would be optional, of course, thus this extension
would be upwards compatible with current Ada. Note that this syntax can
be used with positional association calls, too:

   Proc (in A, out B, in out C);

An alternative, perhaps more English-like, would be to put the mode
keywords in front of the formal parameter:

   Proc (
      in In_Param  => A,
      out Out_Param => B,
      in out In_Out_Param => C);

but I like the first form better, because its form and format are more
familiar, especially when the "=>" are vertically aligned.

-- 
Niklas Holsti
Tidorum Ltd
niklas holsti tidorum fi
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